The objective of this project is to evaluate biological effects and health hazards of selected chemicals and methods for toxicological studies. Emphasis has been on the toxicological assessment of selected metals and metal compounds. Other activities included methods for assessing the effects of chemicals on reproductive function of mammals, other vertebrates, invertebrates, plants, and microorganisms; methods for estimating exposure, and quantifying risk in humans and damage to non-human biota and ecosystems; methods for toxicological testing and evaluation of mixtures of chemicals; and methods for evaluating impairment of physiological functions caused by exposure to chemicals.